The present invention relates to a method of performing a thinning process on a semiconductor wafer.
Hitherto, mechanical methods or chemical methods such as, for example, a grinding method, a polishing method (CMP), and an etching method are known as a method of performing a thinning process on a semiconductor wafer. Generally, these methods all adopt a method in which a protective tape is stuck onto the front surface of a semiconductor wafer having a wiring pattern formed thereon and, after protecting the wiring pattern and fixing the semiconductor wafer, the rear surface of the semiconductor wafer is subjected to a thinning process.
However, according as the process of thinning a semiconductor wafer proceeds, the strength and rigidity of the semiconductor wafer decreases. As a result of this, breaking of the semiconductor wafer due to the decrease in the strength of the semiconductor wafer and warping of the semiconductor wafer due to the decrease in the rigidity are generated. Under these circumstances, full attention must be paid in handling the semiconductor wafers, but even if full attention is paid in handling the semiconductor wafers, there arises a problem of decrease in the yield because the semiconductor wafers are often broken. Further, there is a problem in that the decrease in the strength and rigidity of the semiconductor wafers due to the thinning process makes it impossible to perform a conveying process using a wafer carrier or the like, thereby leading to decrease in the workability.
To resolve these problems, a method is studied in which the front surface of a semiconductor wafer having a pattern formed thereon is fixed onto a hard material such as a quartz plate or an acryl plate, and the rear surface thereof is ground. However, the above-mentioned method involves a problem such that the wafer made of a brittle material is broken in releasing the semiconductor wafer, which is thinned by grinding, from the hard material.
An object of the present invention is to provide a method of thinning a semiconductor wafer so that the generation of breaking or warping in the step of performing a thinning process on a semiconductor wafer using a protective tape can be restrained, and the process of conveying the semiconductor wafer to the next step can be carried out.
Further, an object of the present invention is to provide a method of thinning a semiconductor wafer that can easily release the protective tape after the thinning process.
The present invention has been made in view of these circumstances. As a result of eager studies in order to solve the aforesaid problems, the inventors of the present invention have found out that the aforesaid object can be achieved by the following method, thereby completing the present invention.
The present invention relates to a method of processing a semiconductor wafer, comprising the steps of: sticking a support wafer onto a front surface of a semiconductor wafer having a pattern formed thereon, with a two-sided adhesive sheet; and performing a thinning process on a rear surface of the semiconductor wafer, in a state to which said support wafer is fixed.
According to the above-mentioned method, in performing a thinning process on the rear surface of the semiconductor wafer, the support wafer is fixed via the two-sided adhesive sheet onto the front surface of the semiconductor wafer having a wiring pattern formed thereon, so that even when the semiconductor wafer is thinned by the thinning process, the strength and rigidity are imparted to the semiconductor wafer by the support wafer, and the generation of breaking or warping of the semiconductor wafer in the thinning process can be restrained, thereby making it easier to handle the semiconductor wafers in the thinning process. Furthermore, it is easy to perform a conveying process using a wafer carrier or the like, thereby providing a good workability. Since the support wafer is stuck onto the front surface of the semiconductor wafer with the two-sided adhesive sheet, the protective tape for protecting the front surface of the semiconductor wafer, which tape was conventionally used in the thinning process, is no longer needed. Further, the support wafer makes it easier to release the semiconductor wafer, and the breaking of semiconductor wafers is not generated in releasing the semiconductor wafers as in the case of hard materials.
In the aforesaid method of processing a semiconductor wafer, it is preferable that an adhesive surface of the two-sided adhesive sheet on the side that is stuck onto the front surface of the semiconductor wafer is one whose adhesive force to the front surface of said semiconductor wafer can be reduced after the thinning process.
When a two-sided adhesive sheet having an adhesive surface with the aforesaid property is used, the support wafer can be easily removed from the front surface of the semiconductor wafer in releasing the support wafer after the process of thinning the semiconductor wafer.
In the aforesaid method of processing a semiconductor wafer, it is preferable that an adhesive surface of the two-sided adhesive sheet on the side that is stuck onto the front surface of the semiconductor wafer is a thermoreleasing type adhesive surface.
According to a thermoreleasing type two-sided adhesive sheet having a thermoreleasing type adhesive surface, the support wafer can be removed with ease and certainty from the front surface of the semiconductor wafer in releasing the support wafer after the process of thinning the semiconductor wafer.
Further, the present invention relates to a two-sided adhesive sheet for processing a semiconductor wafer, which is used in the aforesaid method of processing a semiconductor wafer. The aforesaid two-sided adhesive sheet is effectively used in the above-mentioned method of processing a semiconductor wafer according to the present invention.